fkchk is a MySQL InnoDB/XtraDB foreign key checker and repairer. It is useful if you suspect that your database's foreign keys may be broken, or if you disable foreign key checks and now want to be sure that the data is consistent. It is also useful if you have suffered a performance hit and want to check the consistency of foreign keys to verify that they're not the reason. It can attempt to repair any issues it finds, but this option should not be used and is only implemented for testing purposes.
PHP Merge XML is a class that can merge XML documents from strings, files, or DOM objects. The resulting document can be searched using a XPath query string or returned as a string or a DOM object. It provides options to control whether the nodes with the same path or name are replaced or added sequentially.